Apparatus for attaching surgical suture components

ABSTRACT

An apparatus is disclosed for attaching a surgical needle having a generally cylindrical end portion defining an elongated aperture having a generally circular cross-section and a suture having a generally alongated end portion of generally circular cross-section corresponding in dimension to the elongated aperture of the needle. The apparatus includes a pair of dies, each having a generally arcuate surface portion having irregularities including concave portions such that when the cylindrical end portion of the suture is positioned within the aperture of the needle and the dies are positioned about the generally cylindrical end portion of the needle with the surface portions facing the outer surface thereof, the application of inward force to the dies causes the dies to impact the needle and produces inward crimping of the needle so as to attach the needle to the suture. The concave portions define material relief zones to receive and collect deformed material from the needle so as to avoid distortion of the needle. According to the invention, the symmetry of the needle is maintained and the attachment is predictable and superior to those of the prior art. A method of forming such attachment is also disclosed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to surgical sutures and their production.In particular, the invention relates to surgical sutures and apparatusfor the attachment of surgical needles to surgical sutures.

2. Description of Related Art

In the past, surgical needles with an eye for reception of the suturehave been used. As in conventional sewing, the thread is sometimesdoubled through the eye of the needle. The doubled end of the thread inthe eye must pass through tissues during use, which enlarges the openingmade in the tissue. This leads to loss of tightness and increasedtrauma. Because of this problem, there has been a trend towards eyelessneedles in which the end of the suture is attached to the needle so thatthe suture is pulled through the tissue thus minimizing the opening andcausing a minimum of trauma.

The most common surgical suture of this type is a single-use needle ofappropriate size and shape which is crimped to the end of the suture, sothat the needle is used once and then discarded. The attachment can beaccomplished by use of a "drilled end" needle; that is, one in which aconcentric aperture is formed in the end of the needle in which thesuture is placed and the needle crimped around the suture.Alternatively, a "flanged" needle may be utilized in which a U-shapedchannel is stamped into the end of the needle with the ends of the "U"being crimped about the suture to hold the suture together.

The attachment must be one which is: predictably secure; causes aminimum of damage to tissue; is convenient for the using surgeon;permits sterilization; and entails reasonable costs. In addition, theattachment must withstand the rigors of manufacture, sterilization,storage, shipment and use.

During use, it has been found that upon completion of the stitchingprocedure by the surgeon, it is convenient for the surgeon to be able toreadily detach the needle from the suture thus permitting the end of thesuture to be tied or otherwise secured. The needle may thereafter beremoved from the work area so as to avoid harm to the patient, surgeonand other personnel. Cutting the suture with scissors or a scalpel is aconvenient method of disengaging the needle but requires an extrainstrument and an extra manipulation.

More recently, techniques have been developed to attach the suture tothe needle in a manner which permits the surgeon to readily separate thecomponents by merely tugging at the needle at the end of the stitchingprocedure.

The pull required for tugging the needle from the suture is referred toin the U.S. Pharmacopeia as "needle-attachment" or "testing the securityof attachment of eyeless needles" to sutures. For convenience, the term"pull-out" is used.

Experience and testing procedures have determined that the pull-out mustbe at a sufficiently high value that the suture may be placed withoutrisk of the needle becoming detached from the suture during placement;and yet it must pull-out at a value far below the breaking strength ofthe suture and will predictably pull-out before the suture breaks. Inaddition, the suture must pull-out at a value which is reasonablyexertable upon the needle by the surgeon at the time of use.

Conventional crimp operations are difficult to control. Usually a crimpis created between several dies which close to a fixed gap. Anyvariation in: the crimping dies, the needle size, the hole size, or thesuture size alters the degree of crimp. However, with such techniques,the variation can be larger than is acceptable in the manufacture ofcontrolled release or controlled pull-out sutures.

The conventional crimping method requires that the back end of theneedle be struck with two half moon shaped dies. The needle is thenrotated 90° and the dies are arranged to strike the needle a secondtime. In effect, the first strike changes a round hole into one ofeliptical shape, i.e., major and minor axes. The act of rotating theneedle 90° and repeating the operation to some extent, causes the minoraxis to become its counterpart, and the major axis to become the minoraxis thereby completing the attachment in a relatively uniform manner.The effect of this procedure is to distort the end of the needle therebycausing it to lose its symmetry. This last mentioned disadvantageresults in corresponding asymmetry of tissue apertures during use.

The diameter of the suture, the diameter of the needle, theconcentricity of the aperture in the needle, the outside diameter of theneedle, the braid size of the suture, coating material, time andconcentration of baths, and drying conditions are all extremely criticalin predicting and controlling the pull-out force. In addition to sizeeffects, the surface smoothness of the suture and the needle aperture,and lubricants on either components affect the pull-out values. Theconventional method of crimping, as described, underscores many of theseparametric inconsistencies and necessarily utilizes multiple hits toovercome these process variabilities.

To date, techniques devised for connecting such suture components in amanner to perform within the preferred guidelines are not effective inmaintaining needle symmetry and uniformity of dimensions, particularlywith a single hit. The present invention avoids the aforementioneddisadvantages and provides a die and a method for attaching surgicalsutures to needles in a controlled manner while retaining the symmetryof the needle, all with less time and expense.

SUMMARY OF THE INVENTION

The present invention relates to a novel clover leaf die for attachingthe components of surgical sutures which avoids the aforementioneddisadvantages of known techniques while providing suture connectionswhich perform within the desired predetermined parameters. Almostperfect symmetry of the attaching suture needle is maintained.

The novel clover leaf dies are used to attach a suture either in theform of a braid or monofilament, to a drilled end needle. The die istypically used in a suture attaching machine to attach a suture to adrilled end surgical needle.

The novel clover leaf die provides a better method of crimping surgicalneedles to sutures. The novel clover leaf shape provides a more uniformand quicker swage than obtainable using conventional attaching dies.

The invention provides two very significant improvements when comparedto conventional dies. A single hit instead of two or more is used todevelop the compression or swage forces while a uniquely definedirregular shape having concavities for reception of swaged material isprovided. This feature improves the manufacturing economics andreliability of the attaching process. Test reports confirm thatpredictable pull-out forces are achieved in a convenient and controlledmanner using the novel clover leaf shape dies of the present invention.Further, the needle symmetry is maintained in a much improved fashion.The improved needle symmetry is a benefit to the surgeon and themanufacturer.

In a broader sense, the invention relates to an apparatus for attachingtwo members, at least a first member having a generally arcuate outersurface portion and defining an elongated aperture of generally arcuatecross-section, and a second member including at least an end portion ofgenerally arcuate outer configuration corresponding in configuration anddimension to the elongated aperture of the first member. The apparatuscomprises a pair of dies each having an irregular surface portioncorresponding to the arcuate outer surface portion of the first memberand including generally inwardly extending crimping portions spaced by aplurality of concavities defining material relief zones. When the endportion of the second member is positioned within the aperture of thefirst member and the dies are positioned about the corresponding portionof the first member with the irregular surfaces facing the first member,and impact energy is applied to displace the dies toward each other, theinwardly extending crimping surfaces of each die engages the firstmember and transmits inward forces thereto so as to attach the members,while portions of material forming part of the first member adjacentthereto and stricken by the inwardly extending crimping portions arepermitted to be deformed and to collect within adjacent relief zonesdefined by the concavities.

In particular, an apparatus is disclosed for crimping a cylindricalmember for attachment to an elongated member of circular cross-sectionof dimension similar to the inner dimension of the cylindrical member. Apair of dies each has a generally arcuate undulating surface portionincluding concave portions such that when at least an end portion of thesecond member is positioned within the aperture of the first member andthe dies are positioned about the corresponding outer portion of thefirst member, the application of force to the dies toward each othercauses the surface portions of the dies to engage the first member andtransmit inward crimping forces thereto so as to attach the members. Theconcave portions define relief zones which permit deformed material ofthe first member to collect therein so as to avoid distortion of thefirst member.

In the preferred embodiment the apparatus is utilized for attaching asurgical needle having a generally cylindrical end portion defining anelongated aperture having a generally circular cross-section and asuture having a generally elongated end portion of generally circularcross-section corresponding in dimension to the elongated aperture ofthe needle The dies are adapted for attaching a surgical needle to asurgical suture made of at least one of suture materials such as silk,nylon, linen, cotton, polyester, polypropylene, stainless steel, naturalmaterials such as catgut, and synthetic polymers having glycolic acidester linkages subject to hydrolytic degradation to non-toxic, tissuecompatible absorbable components, including polyglycolic acid. Thesurgical suture is made from a material which is braided, twisted ormonofilament. The needle is typically of stainless steel of the drilledend type. Typically, the swaging dies are preferably of a hardenedmaterial such as tungsten carbide, and high speed steels.

A method is also disclosed for attaching a surgical needle having agenerally cylindrical outer end portion and defining an elongatedaperture having a generally circular cross-section, and a suture havinga generally elongated end portion of generally circular cross-sectioncorresponding in dimension to the elongated aperture of the needle,which comprises configuring a pair of dies such that each has agenerally arcuate surface portion having irregularities includingconcave portions, positioning an end portion of the suture within theaperture of the needle, positioning the pair of dies adjacent thecorresponding cylindrical portion of the needle with the surfaceportions facing the generally cylindrical outer end portion of theneedle, applying inward force to the dies to displace the dies towardeach other causing the dies to engage the needle so as to cause thegenerally arcuate portion to engage the surface portion of the needle tothereby cause crimping of the needle and reduction of the averagedimension of the aperture defined thereby, whereby the concave portionsdefine material relief zones to receive and collect deformed materialfrom the needle thereby avoiding distortion of the needle.

Preferably the step of configuring the pair of dies comprisesconfiguring the arcuate surface portion so as to have continuousundulations defined by alternating convexities and concavities. At leastthe portions of the dies defining the generally arcuate surface portionis comprised of hardened material, preferably is tungsten carbide.

According to the method of the invention, the needle may be detachablyattached to the suture so as to be readily separated as mentioned, by aquick tug provided by the surgeon. Alternatively, the needle may beattached with greater pull-out to provide a "non-detachable" suture, inwhich case the suture may be separated from the needle in a moreconventional manner, as by cutting the scissors or scalpel.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described hereinbelow withreference to the drawings wherein:

FIG. 1 is a plan view of a pair of conventional lap-overlap,semi-circular shaped dies;

FIG. 2 is a plan view of a pair of clover leaf swaging dies according tothe present invention with a needle and suture positioned therebetweenfor attachment to each other;

FIG. 2A is a cross-sectional view taken along lines 2A--2A of FIG. 2;

FIG. 3 is an enlarged plan view of a portion of one of the clover leafdies of FIG. 2;

FIG. 4 is a photomicrograph of an end view of a needle with portions ofsutures removed illustrating the effects of the crimping attachmentaccomplished by a pair of clover leaf dies according to the presentinvention;

FIG. 5 is a photomicrograph illustrating a perspective view of the"crimped" needle shown in FIG. 4, and the effects of the dies of thepresent invention on the surface of the needle;

FIG. 6 is a front view of an apparatus with which the clover leaf diesaccording to the present invention may be utilized to attach a suture toa needle by crimping;

FIG. 7 is a side view of the apparatus shown in FIG. 6;

FIG. 7A is an exploded view illustrating the clover leaf dies of thepresent invention mounted in the apparatus of FIG. 7 for attaching asuture to a needle; and

FIG. 8 is an exploded side view of a pair of clover leaf diesconstructed according to the present invention positioned to attach asuture to a curved surgical needle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIG. 1 there is illustrated a pair ofconventional "lap-overlap" dies 10, 12 of the know type utilized toattach a suture to a surgical needle. The working surfaces of the diesare shown at 13 and are each generally semi-circular in shape andinclude overlap regions 11 to receive limited amounts of excess materialoverflowing during the crimping process. The working surface of each die10 shown at 13 is a "lap" region and has adjacent arcuate inner portions11--designated as "overlap" regions--to receive limited amounts ofexcess needle material overflowing during the crimping process. Theoverlap regions are of lesser radii than the lap region and are notconcentric as shown. The lap region is configured and dimensioned toreceive the elongated apertured rear end portion of a surgical needlebetween them.

To attach a needle to a suture, the dies are positioned within anapparatus as will be described hereinbelow. The apparatus is arranged tocause both dies to simultaneously move toward each other and strike theneedle while it is positioned between them. This causes the needle tobecome elliptical in cross-section by portions of metal deforming intoregions 11. This process reduces the average cross-sectional dimensionof the opening. Once the dies are impacted toward each other, they areseparated and the needle is rotated 90°. The dies are then struck onceagain and the attachment is completed. In essence, the first strikecauses the circular aperture in the needle to become elliptical. Thesecond strike completes the attachment and reverses the distortionimparted to the needle. In certain instances additional hits arerequired to secure the suture to the needle. This procedure necessitatesat least a dual step attachment which in turn requires substantial timeand labor. As noted previously, attachments made according to thisprocedure are not always satisfactory for several reasons such asstrength of the attachment, asymmetry of the needle, etc. In such cases,the suture must be discarded. In some instances, multiple hits greaterthan two are required to attach the suture to the needle. This procedurenecessitates additional time and labor.

Referring now to FIG. 2, a pair of dies 14 constructed according to thepresent invention is disclosed. As can be seen each die 14 is identicalto the other and in plan view, has a clover leaf shape which is definedby a generally circular surface having a series of interconnectedalternating individual convex and concave curved surfaces The convexsurfaces are shown at 16 and the concave surfaces are shown at 18. Eachhas a radius generally less than the radius of the primary circularcurve, i.e an imaginary "mean" circle which is shown in dotted lines 21.End portions 25 are preferably shaped as arcuate continuations of the"mean" circle as shown. Each die is shown in position prior to impact ona suture needle 20 having an aperture 22 in which the end portion ofsuture 24 is positioned. During the crimping process, the alternatingindividual convex and concave curved portions 16, 18 allow needlematerial swaged by the crimping action to flow from the convex to theconcave areas and to collect therein thus avoiding the previously knowndeleterious distortion effect of prior art dies. In essence, the dieconverts a single inwardly directed impact into a complex combination ofradial and circumferential forces which in turn provide a combination ofcrimping and swaging forces which attach the needle 20 to the suture 24.The actual crimping action is provided by the convexities 16 and theswaged material reception and collection is provided by the concavities18.

Thus it can be seen that the transformation of a single inward radialforce on the clover leaf dies shown in FIGS. 2-3 not only providesunique attachment of the suture components, but also maintains thesymmetry of the final work product by providing 1) symmetrical inwardforces; 2) concave portions for collection of superfluous materialdistorted or swaged out of position by the attachment; and 3) relativelyminor surface distortion.

Referring now to FIGS. 4 and 5, the photomicrographs illustrate theneedle after the crimping process. The swaged material distorts andcollects about the needle in the areas defined by the concavities 18 ofthe dies 14. This is the result of the complex combination of inwardcrimping forces and the inward and circumferential swaging forcesresulting from a single inward impact force on the dies. As can be seen,the surface of the needle as shown in FIG. 5 includes alternatingconcavities and convexities corresponding to the shape of the needle andthe dies, while maintaining the general asymmetry of the needle.

Referring now to FIGS. 6 and 7 there is shown an exemplary apparatus 26on which sutures may be attached to needles utilizing a pair of theclover leaf dies of the present invention. The apparatus 26 shown ismanufactured and marketed as model 6A Suture Attaching Machine by B.G.Sulzle, Inc., Syracuse, N.Y. Other comparable machines suitable forattaching sutures may be utilized with the dies of the presentinvention.

The suture attaching machine 26 as illustrated in FIG. 6 includes table27 having treadle 28 which is foot operated and connected via treadlerod 30 to suture press 32. The treadle 28 is mounted for pivotalmovement on pivot rod 31.

Referring now to FIG. 7 there is shown a side view of the apparatusshown in FIG. 6. The suture press 32 is encircled and is shown inenlarged form in FIG. 7A. As can be seen in FIG. 7A, the pair of cloverleaf dies 14 which are constructed according to the invention arepositioned within the jaws of the suture press 32 and arranged to bestricken against a needle with the suture components in position asshown in FIG. 8.

The needle 34 shown in FIG. 8 is of a curved type having a straight rearend portion 36 which defines an elongated aperture 38 dimensioned forreception and attachment to an appropriately sized suture 40. The needle34 is supported on a guide support 42 having a "V shaped" guide channelwhich positively determines and positions the needle location andorientation as shown. Thereafter, appropriate adjustments are made topredetermine the strike force to be transmitted to the needle and sutureas may be appropriately calculated to obtain a predetermined pull-outforce. The treadle is depressed to cause the dies to strike the needle.

It will be readily appreciated that the dies of the present inventionare particularly advantageous in that all types of sutures may bereadily attached to needles having an aperture in their blunt end, e.g.,drilled end needles, utilizing a single strike force thereby avoidingthe need to provide "double-hit" attachment as necessary with prior artdies. This procedure provides a suture having a needle which issymmetrical and unaffected by the distorting forces provided by dies andprocedures of the prior art. Moreover, the single-hit attachmentprocedure provides consistent and controlled attachment of the sutureand the needle which additionally reduces the time and effort tocomplete the attachment. Die life is increased; rejected needle/sutureattachments are reduced; and attachment time is reduced. As a result thecost of producing a surgical suture is sizably reduced.

Examples of comparisons of pull-out forces provided by the presentinvention ("Clover lead" die) and prior art ("control") attachments areprovided in the following table.

                  TABLE I                                                         ______________________________________                                        Clover Leaf Die vs. Controls                                                  Size 0                                                                                       Pull-Out Force                                                                Pre-Steriliz                                                                            Post-Steriliz                                        ______________________________________                                        Control 1        (No Data)   n = 10  2.8 kgs                                  VICRYL brand SYNTHETIC                                                        absorbable suture                                                             (Prior Art Double-Hit)                                                        Control 2        n = 10  1.8 kgs n = 10                                                                              1.8 kgs                                Monofilament nylon                                                            suture                                                                        (Prior Art Double-Hit)                                                        Control 3        n = 5   2.6 kgs n = 5 2.9 kgs                                Braided synthetic                                                             absorbable suture                                                             (Prior Art Double-Hit)                                                        Clover Leaf Die  n = 15  3.5 kgs n = 15                                                                              3.3 kgs                                Braided synthetic                                                             absorbable suture                                                             Clover Leaf Die  n = 15  2.9 kgs n = 15                                                                              3.4 kgs                                Monofilament nylon                                                            suture                                                                        ______________________________________                                    

The foregoing table clearly illustrates and underscores theeffectiveness of the present invention in providing consistent andcontrolled needle/suture attachments using a single hit. In fact, ineach case the attachments made according to the invention exhibitedpull-out forces to separate the suture from the needle at least equal tothose of the prior art double-hit (or multiple hit) attachments In eachinstance the attachment of the present invention was accomplished by asingle-hit procedure, in a fraction of the time, and provided a strikezone in the needle free of distortions or cold working effects. The lastmentioned adverse effect can be expected with prior art needle-sutureattachment methods.

The swaging dies of the present invention may be utilized with all typesof needles such as curved needles, straight needles, or the like,provided they have an elongated aperture on their end portion forreceiving the suture. Sutures usable with the present invention includesilk, nylon, linen, cotton, polyester, polypropylene, stainless steel,natural materials such as catgut, synthetic polymers having glycolicacid ester linkages subject to hydrolytic degradation to non-toxictissue compatible absorbable components, including polyglycolic acid.The sutures may be monofilamentary or braided, absorbable ornon-absorbable. The dies of the present invention are preferablyconstructed of a hardened material such as tungsten carbide. However, itshould be understood that all materials suitable for such dieconstruction may be used, provided the geometric and configurationalparameters taught by the present invention are met.

We claim:
 1. Apparatus for attaching two members, at least a firstmember having a generally arcuate outer surface portion and defining anelongated aperture of generally arcuate cross-section, and a secondmember including at least an end portion of generally arcuate outercross-sectional configuration corresponding in configuration anddimension to the elongated aperture of the first member, which comprisesa pair of dies each having an inner die surface portion corresponding tothe arcuate surface portion of the first member and including generallyinwardly extending crimping portions spaced by a plurality ofconcavities defining material relief zones, said inward crimpingportions being substantially equal said concavities such that when theend portion of the second member is positioned within the aperture ofthe first member and said dies are positioned about the correspondingportion of the first member with said inner die surface portions facingthe first member, and inward force is applied to displace said diestoward each other, said inwardly extending crimping portions of each dieengage the first member and transmit inward forces thereto so as toattach the members by forces distributed substantially uniformly aboutthe second member while portions of material forming part of the firstmember adjacent thereto and engaged by said inwardly extending crimpingportions are permitted to be deformed and to collect within adjacentrelief zones defined by said concavities so as to attach the memberswhile maintaining substantially the same cross-sectional character ofthe first member thereby crimped.
 2. Apparatus for crimping a firstcylindrical member defining an elongated aperture for attachment to asecond elongated member of generally circular cross-section of widthwisedimension similar to the widthwise dimension of said aperture of saidfirst cylindrical member, which comprises a pair of dies, each having agenerally arcuate undulating surface portion including alternatinginwardly extending convex and substantially equal concave portions suchthat when at least an end portion of said second member is positionedwithin the aperture of the first member and said dies are positionedabout the corresponding outer portion of the first member, theapplication of inward force to said dies toward each other causes atleast portions of said undulating surface portions of said dies toengage the first member and transmit inward crimping forces distributedsubstantially uniformly about the second member so as to attach themember, whereby said concave portions define relief zones which permitdeformed material of the first member to collect therein so as to attachthe members while maintaining substantially the same cross-sectionalcharacter of the first member in the area engaged by said dies. 3.Apparatus for attaching two members, at least a first member having agenerally cylindrical outer portion and defining an elongated aperturehaving a generally circular cross-section, the second member including agenerally elongated end portion of generally circular cross sectioncorresponding in dimension to the elongated aperture of the firstmember, which comprises a pair of dies each having a surface defined bya plurality of alternating substantially equal convexities andconcavities such that when the second member is positioned within theaperture of the first member and said dies are positioned about thecorresponding portion of the first member and impact energy is appliedto said dies to displace said dies toward each other, said convexitiesof each die engage the first member and transmit inward crimping forcesthereto so as to attach the members while portions of material formingpart of the first member adjacent the areas engaged by said convexitiesare permitted to be deformed and to collect within adjacent relief zonesdefined by said concavities thereby maintaining substantially the samecross-sectional character of the first member in the area crimped. 4.Apparatus for attaching a surgical needle having a generally cylindricalend portion defining an elongated aperture having a generally circularcross-section and a suture having a generally elongated end portion ofgenerally circular cross-section corresponding in dimension to theelongated aperture of the needle, which comprises a pair of dies, eachhaving a die face defined by a generally arcuate surface portion havingirregularities including substantially equal concavities and convexitiessuch that when the cylindrical end portion of the suture is positionedwithin the aperture of the needle and said dies are positioned about thegenerally cylindrical end portion of the needle with said surfaceportions facing the outer surface thereof, applying inward crimpingforce to said dies causes said dies to impact the needle and produceinward crimping forces distributed substantially uniformly about theneedle so as to attach the needle to the suture whereby said concaveportions define material relief zones to receive and collect deformedmaterial from the needle so as to maintain substantially the samecross-sectional character of the needle in the area crimped.
 5. Theapparatus according to claim 4 wherein said needle is manufactured ofstainless steel.
 6. The apparatus according to claim 5 wherein saidgenerally arcuate surface is defined by a plurality of continuousundulations having alternating convexities and concavities, saidconvexities each having its crest radially inward of a "mean" imaginarycircle and said concavities each having its crest radially outward ofsaid "mean" imaginary circle.
 7. The apparatus according to claim 6wherein said radial distance between the crest of each convexity andsaid "mean" imaginary circle is substantially equal to the radialdistance between the crest of each concavity and said mean circle. 8.The apparatus according to claim 7 wherein said arcuate surface portionof each die intersects the die face at two end positions, the arcuatesurface immediately adjacent each end portion being congruent with said"mean" imaginary circle.
 9. The apparatus according to claim 8 whereinsaid dies are adapted for attaching a surgical needle to a surgicalsuture made of at least one of suture materials such as silk, nylon,linen, cotton, polyester, stainless steel, polypropylene, naturalmaterials such as catgut, and synthetic polymers having glycolic acidester linkages subject to hydrolytic degradation to non-toxic, tissuecompatible absorbable components, including polyglycolic acid.
 10. Theapparatus according to claim 9 wherein said pairs of dies are adapted toattach a surgical suture made from a material which is braided, twistedor monofilament.
 11. The apparatus according to claim 10 wherein saidswaging dies are manufactured of a hardened material such as tungstencarbide.